Soil analysis by radiant energy



Feb. l2, 1946. E. I IPsoN SOIL ANALYSIS BY RADIANT ENERGY 2 sheets-sheet -1 Filed July' 6, 1942 Feb. 12, 1946. E. I IPSON SOIL ANALYSIS BY RADIANT ENERGY Filed July e, 1942 I 2 Sheets-Sheet 2 EDWA HD L/Pso/v,

INVENTOR.

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l UNITED s'rArs posits.

Patented Feb. 12,1946

s 'PATENT SOIL ANALYSIS BY ENERGY Edward Lipson, Houston, Tex. Appllitin Jill! 6, 1942, Serial N0. 449,922

5 claims. (ci. 25o-sas) This invention relates to method and appara.- tusfor locating hydrocarbon deposits, and more particularly to the analysis of soil samples for information directly indicative of the location, nature and extent of such deposits.

It iswell known that gas seeps ydetectable from odor or by the presence of gas bubbles over a water-covered area are directly indicative of the presence of subsurface buried deposits of oil and gas. Where such seeps are small, as is usually the case, it has been proposed to detect the seeps and determine their areal extent by quantitative analyses which determine the concentration of surface entrapped hydrocarbons or certain solids which result from the mutual presence of hydrocarbons or other chemical constituents of the soil through which the gases pass. A quantitative x determination of these seeps is therefore a direct method of detection of the buried deposits of which the presence and location are sought.

The present invention is based upon the discovery that the earth materials, or soil, above or proximate hydrocarbon deposits are in some manner modified by the constituents which migrate through the soil, whereby vthe opacity or absorption factor of such materials to the transmission of radiant energy is an index or the location, proximity and areal extent of the de- It is uncertain as to the exact nature of the modification which takes place inthe earth materials and which is utilizedl in the practice of the invention. A plausible explanation is that the great pressure to which hydrocarbon deposits are subjected in the earth produces a certain amount of disassociation of the highly complicated hydrocarbon compounds and that such disassociation produces heavy natural gases. Y

As above explained, these heavy gases, and others, migrate upwardly and during their migration dissolve or pick up some of the minerals in the soll. As-these products approach the surface the gases gradually diffuse into the atmosphere and leave minerals behind, whereby such minerals produce an increased opacity or absorption factor of the soil to the transmission of radiant energy.

As already pointed out, it is uncertain as to the exact nature of the soil modification which takes place and which is utilized in the practice of the present invention Ths foregoing is offered merely as a plausible explanation and it is not intended; that th scope of the invention valuable subsurface hydrocarbon deposits by the investigation of soil samples proximate or overlying the deposits,.whereby the opacity or absorption factor of such soil is an. index of the presence zo The foregoing objects are primary objects and of the deposits. l

It is also an object of the invention to locate subsurface hydrocarbon deposits by a study of samples of soil systematically obtained from preselected areas at or near the earths surface.

Still another object is to determine the nature of formations penetrated byy well bores by determining the variations in the absorption factor of cuttings or samples which are taken at different depths within the well bore.

Another object is the provision of apparatus for determining the variations in the absorption factor of soil samples by subjecting the samples to radiant energy and measuring the absorption of such energy by the respective samples.

will, together with other objects, be more fully apparent from reference to the following description taken in connection with the accompanying drawings in which:

:i Fig. 1 is a schematic diagram of apparatus utilized in the practice of the invention;

Fig; 2 is a sectional view through one form of mechanism for subjecting soil samples to radiant energy so that the absorption factor of such samples may be-measured;

Fi 3 is a sectional view in elevation of a mec nism which may be utilized for measuring the absorption of soil samples'in situ;

Fig. 4 is a sectional view taken on 4-4 in Fig. 3:

Fig. 5 is a similar sectional view taken on the line 5-5 in Fig. 3.

Themethod of the invention comprehends the' procurement of samples of earth material, or soil, in an area to be investigated. It is to be understood that the samples may be systematically obtained over a relatively large area and that such samples may then be taken to a location has been advanced.

It is a primary object for analysis in the manner hereinafter described. Alternately, the invention also comprehends that, if desired, samples may be investigated in situ. The invention is also utilized in providing information as to the location of productive strata penetrated by bore holes, and it is intended that the invention as described and claimed shall include the investigation `of samples, such as cuttings or sidewall samples, obtained from different elevations Within a bore hole.

Referring first to Fig. 2 of the drawings, one

of the inventiontolocate. u embodiment of apparatus of the invention cathe line shield member I of material having a high atomic weight, such' as lead, such member having a counterbore 2 in one end thereof and a smaller inner bore 3 centrally thereof. A quantity of radioactive material 4 is positioned within the bore 3 and serves to provide the desired radiant energy whereby the absorption factor of a soil sample may be determined. l

It has been found that one milligram of radium serves satisfactorily as the radioactive substance 4, since such materialis a prolific source of.

gamma rays which are*l extremely penetrating, and hence rapid observations may be made. It is pointed out, however, that other sources of radiant energy may be utilized, such as other radioactive substances or. with alarger installation, a suitable source of X-rays may be used.

Extending outwardly from within the counterbore 2 is a shielding tube 5, such asked. .and a lead plate 3` surrounds this tube adjacent the mouth of the counterbore 2 to assist in protecting the operator from the radiations from the source 4. A lead plug 1 is also providedwithin the tube ,5 and this plug is of a selected thickness so that the rays passingtherethrough are of sufv traemos pable of carrying out the method comprises aL the amplifier for the unit 30 or, if desired, such power supply may be incorporated as a part of the unit.

The quantity of energy from`the source which is passed throughthe test sample 21 produces impulses which 'constitute the output of the ionization chamber and the amplifier unit III, and such impulses are transmitted to the unit 30 which is connected by means of a conductor 32 to a mechanical counter 33 whereby the quantity of energy passing through the sample 21 may be determined by the readings of such counter.

In order that additional information may be had as to the quantity of energy passing through the test sample 21, a portion of the output from the amplifier of the unit 30 is utilized as the input to a frequency meter 35 and 'also as the input to the amplifier 36 of which the output is utilized toactuate the mechanism within the recorder 31 so that there is provided a wave trace 38 as the frequency meter 35 and the graphical record 38 ther be made in connection withvFig. 1 of the 1 drawings.

'Ihe Locher tube I2 is adjacent an opening Il in the wall of the housing I I and shield plate I3.

A shielded passage ,is provided between this open ing and the end of the tube 5 by the enlarged tubular member 20 having av reduced section 2I adjacent the opening I3.

A slidable shield 25 has one end which fits over the larger end of the member 20 and the other end of this shield ts closely about the outer end of the tube v5. This slidable shield is movable to the position shown in dotted outline at 25' and when in this position, a container 28,

such as aluminum, containing a sample of earth material may be positioned within the passage through which energy from the source 4 may pass to the Locher tube I2.

The sample in the container 25 may be in any 55 of various forms. For example, such sample may be solid, comminuted, or may be liquid or semi-liquid in form. The principal requirement is that successive samples be prepared in substanchamber within this unit is supplied with power from the source 28. The amplifier of the unit I0 is provided with power from a separate source 29 which also supplies power for the multi-vibrator and amplifier unit 33.

A bias power supply 3| may be provided for produced by the recorder 31 indicate the amount of energy that traverses the test sample 21. With this information available, it is possible to determine the opacity or absorption factor of the sample 21.

'I'he absorption factor is obtained in the manner above set forth for a plurality of samples which have been taken in a systematic manner in the area under investigation. Hence, a comparison or composite of the information thus obtained can be utilized for plotting a map of the investigated area. In event such area overlies or is proximate subsurface hydrocarbon de posits, this fact will be revealed by the com-l parative values of the absorption factors of the various samples.

Inasmuch as the rate of emanation of ,the quantityl of energy from the source I varies considerably, it is desirable to provide a separate measuring circuit similar to that already described as comprising elements I3 and 21 to' 3S, inclusive. This circuit is identified by similar primed reference characters, the only difference Ibeing that the standard sample 21 is 'maintained constant and is preferably of less opacity than the test samples 21. A portion of the radiant energy is directed through each of the samples and the o graphical record 38 produced by the energy transmitted through the standard sample enables a determination of the relative transmission of such energy through the standard and test` samples. It will be noted that the trace 38' for the standard sample shows larger variations than they are in the test sample having the largerl opacity. The traces 38 and 38' may represent the readings of several samples one after the other and the lengthof the trace will depend upon the length of time that a sample remains under test.

l going description over various areas having known characteristics have revealed that the present invention is capable of locating subsurface deposits with a high degree of accuracy. This has also been found true where the invention is utilized for determining the relative absorption factor for samples taken from different elevations within a well bore.

The invention is not confined to the making of analyses in the laboratory, but also comprehends the use of equipment whereby observations may be made in the field, the samples being examined in situ in the manner indicated in Figs. 3, 4`and of the drawings. In this form of apparatus the source 4 oi radiant energy is positioned within the shield I' which is attached through a connector member 4-5 to the housing I0' within which the Locher tube I2 is located. Radiant energy from the source 4 is directed through the opening 46 to and through the mass or sample 41 of earth material about which so-il has been removed so that the portable unit may be placed thereover as indicated in Fig. 3.

The energy passing through the sample 41 enters the window 48 in the. inner wall of the housing I0 and thence enters the Locher tube I2 and produces ionization therein. This ionization gives rise to electrical impulses within a circuit such as above described and hence enables an examination of the sample 41 without removal of s uch sample from position at or proximate the surface of the earth.

Broadly, the invention comprehendsv novel method and apparatus for determining absorption factors of soil samples as an indication of the location, nature and extent of subsurface hydrocarbon deposits.

What is claimed is:

1. In the logging of wells the method comprising the steps of obtaining formation samples at different levels within a well, applying radiant energy such as gamma rays to the samples, and measuring the relative amount of radiant energy transmitted through different ones of said samples as an indication of'the hydrocarbon content of such samples due to the original proximity of the samples to formations containing hydrocarbon iluids.

2. In the art o! exploration for subsurface deposits from which leakage occurs and produces alteration of opacity of earth materials at points spaced from the deposits, the method of locating the deposits comprising. subjecting samples of earth materials to gamma ray or the like radiant energy, and determining the relative quantity of energy transmitted through said samples due to the proportion of leakage thereinto as an indication of the proximity of the samples to the subsurface deposits.

3. In the art of exploration for subsurface deposits froxn which leakage occurs and produces alteration of opacity of earth materials at points spaced from the deposits, the method of locating the deposits comprising, subjecting samples of earth materials to gamma ray or the like radiant energy, simultaneously subjecting a standard sample to the radiant energy, measuring for a predetermined time interval the quantity of energy passing through the respective samples, and' determining from such measuring step a comparison of the earth. with the standard sample to obtain the opacity of the earth sample.

4. Apparatus for determining the location of subsurface hydrocarbon deposits by examination of soil samples which have been modified by emanations passing from the deposits to the formations from which suchy samples have been obtained comprising, in combination, a source of gamma ray orthe like radiant energy. means directing energy fromisaid source to a soil sample, andmeans responsive to radiant energy passing through the sample whereby the relative opacity of a plurality of the samples is obtained.

5. An apparatus of the character described comprising a. metal shield, a source of gamma rays therein, a shield permitting the passage of a predetermined intensity of such rays. a shield tube to receive such last rays, a sample of an earth formation being investigated adapted to be disposed in such tube, a shield tocontrol a ilow of gamma rays from said sample, and an ionization chamber to detect such rays as an indication of the radioactive content of such sample.

EDWARD LIPSON. 

